Constant web tension unwinding mechanism



y 1960 R. LE BARON BOWEN, JR 2,937,819

CONSTANT WEB TENSION UNWINDING MECHANISM 4 Sheets-Sheet 1 Filed Sept.50, 1955 INVENTOR. RICHARD LEBARON BOWEN,JR.

BY .MMM $3M film ATTORNEY y 1960 R. LE BARON BOWEN, JR 2,937,819

CONSTANT WEB TENSION UNWINDING MECHANISM Filed Sept. 30, 1955 4Sheets-Sheet 2 I62 /60 70 ii. a I43A /4 INVENTOR. RICHARD LEBARONBOWEN,JR.

ATTORNEY y 1960 R. LE BARON BOWEN, JR 2,937,819

CONSTANT WEB TENSION UNWINDING MECHANISM Filed Sept. 30, 1955 4Sheets-Sheet 4 FIG. 6 V

l F 7 I50 INVENTOR. RICHARD LEBARON BOWEN,JR.

BY 322144;, jedefl z hhwk ATTORNEY United States Patent CONSTANT WEBTENSION UNWINDIN MECHANISM Richard Le Baron Bowen, Jr., 173 ColumbusAve., Pawtucket, RI.

Filed Sept. 30, 1955, Ser. No. 537,855

13 Claims. (Cl. 242-755) This invention relates to a constant webtension unwinding mechanism and more particularly to a mechanism formaintaining a constant speed on the web unwinding mechanism through avariable speed transmission responsive to the change in brake speedwhich reacts to control the speed of the brake.

One of the objects of the present invention is to provide a constantbraking force in a web unwinding mechanism.

Another object of the present invention is to provide a braking forcemechanism which inherently will permit the accurate duplication of thebraking force.

Other objects of the present invention will be pointed out in part andbecome apparent in part in the following specification and claims.

The present application is a continuation-in-part of my copendingapplication Serial No. 344,520, filed March 25, 1953, now Patent No.2,781,178, dated February 12, 1957.

Uniform tension is a prerequisite to uniformity of product in many webprocessing machines used for textiles, paper, imitation leather,printing and the like. Especially is this true in coating machinerywhere the tension on the web effects the nature of the application ofthe coating being applied to the web, which may be paper, cloth, orplastic. When a supply roll of web material is placed in the machine thecloth is drawn off at a constant speed and at a given tension. As thediameter of the supply roll decreases the speed or linear travel of thecloth is maintained constant. However, the tension on the clothincreases as the drag on the supply roll increases. There fore, it isnecessary to regulate the drag or friction onthe supply roll shaft ifthe tension on the cloth is to be maintained constant. Past devices havefailed to automatically control the drag and thereby regulate thetension accurately in accordance with the changing tension produced asthe supply roll decreases in diameter.

This failure was due in part to the nature of the braking mechanism,which consisted of the conventional arrangement of a brake drum and ashoe provided with a brake lining. Periodic adjustment was necessary toreduce the braking force as the rotational speed of the unwinding rollincreased.

Referring to the drawings in which similar characters of referenceindicate corresponding parts in all the figures:

Figure 1 shows an embodiment of the present invention in diagrammaticform, for the sake of clarity and simplicity, and presents the mechanismas applied to an unwinding device.

Figure 2 is a diagrammatic embodiment of a modified form of themechanism illustrated in Figure 1.

Figure 3 is a diagrammatic form of an electric brake.

Figure 4 is a diagrammatic form of mechanism which is still anothermodification of the mechanism illustrated in Figure 1.

Figure 5 is a diagrammatic form of mechanism which is still anothermodification of the mechanism illustrated in Figure 1;

Figure 6 is a diagrammatic form of another modification of Figure 1. j a

Figure 7 is a modified form of Figure 6.

Referring to the drawings and particularly to Figure 1', a strip or webof material 11 is being withdrawn from a beam 12 by means of a drum 16.Beam 12 is secured to an axle 13 which has fixed to it bevel gear 14which meshes with bevel gear 15 fixed to a shaft 20 of a continuouslyvariable speed transmission, generally indicated by reference character17. A second shaft 21 of variable speed transmission 17 is operativelyconnected to a brake generally indicated by reference character 150through a shaft 36, sprocket 33 fixed to shaft 36, sprocket 32 fixed toshaft 21, and chain 34 connecting sprockets 32, 33.

Fixed to the other end of shaft '36 is bevel gear 151 which meshes withbevel gear 152 fixed to brake drum 153 of brake 150. Brake drum 153iscontacted by brake shoe 154 which is prevented from rotating as at point155. Brake shoe 154 is compressed on drum 153 by means of adjustingscrew 156. Loosening screw 156 permits drum 153 to rotate freely.Tightening screw 156 tends to restrain drum 153, and therefore alsotends to restrain transmission 17 and roll 12 from rotating.

The variable speed transmission 17 comprises the pair of shafts 20 and21 which extend parallel to each other and are rotatably mounted in ahousing 22. Each shaft 20, 21 carries a pair of coned disks 23, 24respectively, forming expansive V pulleys which are splined to saidshafts. Coned disks 23, 24 are operatively connected through edge-activebelt 25 and may be simultaneously and oppositely adjusted to providevariable speed by the simultaneous adjustment of levers 26 and 27 whichare operatively connected to coned disks 23, 24 and pivotally separatedby lever 28. The levers 26, 27 are fixed at one end thereof to threadedshaft 30 by means of threaded bearings 31, 132. The rotation of threadedshaft 30' through slip clutch 29 vsimultaneously and oppositely movesdisks 23, 24 on shafts 20, 21 thereby varying the speed of rotation ofshaft 20 relative to shaft 21. Threaded shaft 30 is controlled by adifferential gear train generally indicated by reference character 58.

The differential gear train 58 comprises three shafts '60, 61, 62rotatably mounted in housing 63. Short stub shafts 64 and 64A projectfrom block 62A fixed to shaft 62. Shafts 64 and 64A have rotatablymounted thereon bevel gears 65 and 66 which are operatively connected tobevel gears 67 and 68 rotatably mounted on shaft 62. A spur gear 70fixed to bevel gear 67 meshes with spur gear 71 fixed to shaft 60.Sprocket 72 fixed to bevel gear 68 is operatively connected by means ofchain 73 tosprocket 7.4 fixed to shaft 61. It is evident that shafts.60, 61 when rotated in the same direction and at the. same speed causeshaft 62 to remain idle. However, any

difference in speed of shafts 60, 61 when turning in thesame direction,will cause shaft 62 to rotate, the speed of this rotation beingproportional to the difference in the speeds of shafts 60, 61.

Shaft 61 of differential 58 is operatively connected with drum 16through bevel gear 75 fixed to drum 16 which' meshes with bevel gear 76fixed to shaft 77, on which isfixed sprocket 78 which is connected tosprocket 80 fixed; to shaft 61 by means of chain 81. Shaft 60 ofdifferential 58 is operatively connected to shaft 21 of transmission 17by means of sprockets 82, 83 and chain 84 and has a handwheel 85 securedthereto. Shaft 62 of differential58 is operatively connected to threadedshaft 30 of trans-' mission 17 through a slip clutch 29 by means ofsprockets 46, 47 and chain 48, sprocket 47 being fastened toslip clutch29.

is withdrawn at a constant linear velocity. When 'the system is atequilibrium, shafts 60, 61 of difierential 53 are revolving at the samespeed and shaft 62 is motionless. Shaft 61 is driven at a constant speedby a driving connection with drum 16, which rotates at constant speed.

As beam 12 unwinds, its diameter decreases and its speed of rotationincreases. This increase in speed is immediately transmitted to shaft 60of difierential 58 from shaft 21 of transmission 17. As soon as there isa difference in speeds between shafts 60, 61 of direrential 58, shaft 62commences to rotate, thereby changing the speed of transmission 17 andthus maintaining the speed of shaft 21 constant. Since the speed ofshaft 21 is maintained constant, the speed of brake 150 is likewisemaintained constant, and thus the power and tension applied to the webare also constant.

Figure 2 diagrammatically depicts a modified form of mechanism forcontrolling the variable speed transmission 17, and thus is a modifiedform of Figure 1. Here the, speed ratio of transmission 17 is changed bymeans of a hydraulic system rather than the mechanical screw used inFigure 1. The hydraulic control device consists of a fluid motorcomprising a cylinder 140A connected to move with lever 26A, and apiston 141A reciprocally mounted in the cylinder 140A and operativelyconnected to lever 27A, together with valving means 142A for controllingthe relative movement of cylinder 140A and piston 141A. Valve 142A is afour way bydraulic valve with a control lever 143A operatively connectedto shaft 62 of differential 58 by means of bevel gear 160 fixed to shaft62 meshing with bevel gear 161 which has fixed to it lever 162. Link 163connects lever 162 to control lever 143A.

This piston type of hydraulic control is well known in the art and hasbeen described by Clay in Patent No. 2,306,541. Oil is supplied to thecontrol valve through line 144A, and oil is returned from the cylinderby line 146A. Hydraulic fluid is supplied to the system by means ofhydraulic pump 164 which has a suction line 165 which connects withfluid reservoir 166. The construction of this type of four way hydraulicvalve 142A has been well disclosed by Clay. Hydraulic pump 164 is drivenby a constant speed power source, such as a motor not shown. Hydraulicpump 164 might well be driven from shaft 21 of transmission 17 whichalso turns at a. constant speed.

As previously described for Figure 1, when beam 12 unwinds, shafts 20,21 and brake 150 will tend to gradually increase in speed. This increasein speed is immediately transmitted from shaft 21 to shaft 60 todifferential 58. As soon as there is a difference in speed betweenshafts 60, 61 shaft 62 commences to rotate thereby moving valve lever143A and introducing oil to cylinder 140A causing the piston 141A tomove cones 24 together and simultaneously move cones 23 apart, thereby.restoring the speed of the brake to its arbitrarily set initial value.

After the beam has been unwound, the transmission is at one limit. Withthe mechanism stopped, valve lever 143A is held from movement becausedifferential shaft 62 has stopped. For starting another beam. ofmaterial the transmission should; be shifted back to the startingposition. To accomplish this, handwheel is turned. This accomplishes twothings. In the first place, since shaft 61 of differential 58 does notmove, movement of shaft 60 produces motion in shaft 62 and thus movesvalve lever 143A. Movement of levers 26A, 27A would not shiftthetransmission unless the sheeves 23, 24 were rotated. Rotation ofhandwheel 85 also rotates sheeves 23, 24..

Figure4 diagrammatically depicts a modified form of mechanism forcontrolling the variable speed transmission 17, and thus is amodification of Figure 1. This comprises abell crank arm 100 pivotallymounted at 101 to a bracket 102 secured to housing 22 and having afollower roller 103 rotatably mounted at 104 which bears against theoutside diameter of beam 12 to sense the decrease in the size of beam12. A link 105 is pivotally mounted to hell crank arm 100 at 106 and tolever 27 at 107. A link 108 pivotally mounted to bell crank arm 100 at110 connects to lever 26 at 111. A spring 112 is connected to bell cranklever 100 at 113 and to housing 22 at 114. The spring 112 causes thefollower roller 103 to ride against beam 12.

In operation it is self evident that as the diameter of the beam 12decreases, bell crank lever 100 will move levers 26 and 27 thus changingthe speed of the transmission 17. This movement will maintain the speedof shaft 21 essentially constant. Since the speed of shaft 21 ismaintained constant, the power applied by brake 150 will likewise remainconstant, thereby applying constant tension to the web 11.

Figure 5 diagrammatically depicts a modified form of mechanism forcontrolling the variable speed transmission 17, and thus is amodification of Figure 1. Here there is a governor generally indicatedby which controls the current to an electric motor 44 which changes thespeed of'the transmission.

Governor 120 consists of a rotatably mounted shaft 121 to which is fixedconnector 122 and on which is slidably mounted flange 123. Arms 124 arepivotally mounted to connector 122, and links 125 connect arms 124 withflange 123. When flange 123 rises, it makes contact with switch 126which connects with wire 54. Wire 51 contacts shaft 121 at 127. Shaft121 is operatively connected to shaft 36 of brake by means of sprockets130, 131 and chain 132.

As previously described, when beam 12 unwinds, shafts 20, 21, shaft 36and brake 150 tend to increase in speed. Since shaft 121 of governor 120is operatively connected to shaft 36, the governor will also increaseits speed of rotation. As the speed increases, arms 124 are thrownoutward by centrifugal force, and flange 123 rises to make contact withswitch 126. This closes the electrical circuit and current is suppliedto motor 44 through wires 50 and 51. To reset the mechanism after a beamhas ben unwound, reversing switch 53 and handwheel 56 are used.

Motor 44 could be controlled by other electrical. switches responsive tochanges in speed, such as other centrifugal switches or the speedresponsive switch shown. by Butterworth et al. in Patent No. 2,392,226.

Figure 6 diagrammatically depicts a modified form of mechanism forcontrolling the variable speed transmission 17, and thus is amodification of Figure 1. This comprises gear pumps and 171 andhydraulic motor 172. Pumps 170, 171 are connected to reservoir byconduits 173 and 174. Pumps 170, 171 are connected to each other byconduits 176, 177. Motor 172 is connected to conduits 176, 177 byconduit 178, and to reservoir 175 by conduit 180.

Pump 170 is driven from drum 16. Fixed to drum' 16 is bevel gear 75which, meshes with bevel gear 76 fixed to shaft 77 which has sprocket 78fixed to the other end. Sprocket 78 is operativelyconnected to sprocketS0 fixed to pump 170 by means of chain 81. Pump 171 is operativelyconnected to shaft 21 of transmission 17 by means of sprockets 82, 83and chain 84. Motor 172 is operatively connected to shaft 30 by means ofsprockets 46, 47 and chain 48. Sprocket 47 is fixed to slip clutch 29.

Pump 170 is driven at a constant speed from drum 16. When the system isin, equilibrium pump 171 travels at the samespeed as pump 170. Whenpumps 171,and 170* travel at the same speed they have the samevolumetric displacement. When pumps 170, 171 travel at: thesame speed,fluidis drawn from reservoir 175.through conduit 173 by pump 171 and ispassed through conduits 176,177

to the suction of pump 170. Thence the fluid goes through the conduit174 to reservoir 175. As the beam 12 unwinds, the speed of rotation ofshaft 21 increases, thereby increasing the speed of rotation of pump 171relative to pump 170. This increase in the speed of pump 171 deliversmore fluid than pump 170 can discharge. The excess fluid passes throughconduit 178 and causes hydraulic motor 172 to revolve, turning speedchanging screw 30. Fluid is returned to reservoir 175 through conduit180.

When one beam has been unwound and removed, the unwinding mechanism mustbe reset for a new beam. To accomplish this, handwheel 56 is turned in adirection to cause pump 171 to discharge fluid through conduit 173.Conduit 176 becomes the suction line for pump 171. Since pump 170 is notfree to rotate, fluid is drawn through conduit 178 thereby turning motor172 and shifting screw 30 so that transmission 17 is shifted to thestarting position.

Figure 7 shows how this same modification can be applied to theembodiment shown in Figure 2. Here the fluid motor takes the form of acylinder and piston. Conduit 178 connects to one end of cylinder 181 andconduit 183 connects with reservoir 175. Piston 182 is operativelyconnected to control arm 143A of Figure 2.

In all the embodiments of the present invention a mechanical brakegenerally indicated by reference character 150 has been shown as thebraking means for applying tension to the web of material. However, inall examples an electric brake such as shown by 190 in Figure 3 may beused. Electrical brakes are well known in the art and may be ofelectromagnetic nature, of eddy current design, or of the type known asthe magnetic particle brake. All will perform equally well. The magneticparticle type of brake is particularly advantageous since the wear isvirtually negligible.

Having shown and described preferred embodiments of the presentinvention, by way of example, it should be realized that structuralchanges could be made and other examples given without departing fromeither the spirit or scope of this invention.

What I claim is:

1. In a constant tension web unwinding mechanism, an axle, a beamcarrying said web material, said beam being mounted on said axle, abrake comprising a rotatable drum and a brake shoe frictionally engagingsaid drum and held stationary, a variable speed transmission comprisingtwo power transmitting shafts and a speed changing mechanism, a drivingconnection between said axle and one of said power transmitting shafts,a driving connection between said brake and the second of said powertransmitting shafts, said transmission being driven by said axle, andmeans for automatically maintaining the speed of said brake constant,thereby compensating through said variable speed transmission for thevariable speed of said axle to render the power applied to said axleconstant, said brake being driven solely by the said second powertransmitting shaft.

2. In a constant tension web unwinding mechanism, an axle, a beamcarrying said web material, said beam being mounted on said axle, abrake comprising a rotatable drum and a brake shoe frictionally engagingsaid drum and held stationary, a variable speed transmission comprisingtwo power transmitting shafts and a speed changing mechanism, a drivingconnection between said axle and one of said power transmitting shafts,a driving connection between said brake and the second of said powertransmitting shafts, said transmission being driven by said axle, andmeans responsive to the rotation of said second shaft for maintainingthe speed of said brake constant, said brake being driven solely by thesaid second power transmitting shaft.

3. In a constant tension web unwinding mechanism, a beam carrying theweb, a drum operatively connected to said web and over which said webtravels at a constant linear speed, said beam being rotated-by unwindingof the web therefrom, a variable speed transmission provided with afirst shaft, a second shaft, and speed changing mechanism, said firstshaft being driven by said beam, a brake comprising a rotatable drum anda brake shoe frictionally engaging said drum and held stationary, saidsecond shaft driving said brake drum, and a differential gear train formaintaining the speed of rotation of said second shaft constant, saidbrake being driven solely by the said second shaft. 7

4. In a constant tension web unwinding mechanism, a beam carrying theweb, a drum over which the web travels at a constant linear speed, avariable speed transmission comprising a first shaft, a second shaft,and a speed changing shaft, said first shaft being driven by said beam,a brake, said second shaft driving said brake, a differential gear trainhaving three power transmitting elements, said second shaft driving oneof said elements, a slip clutch, a drive connection between said speedchanging shaft and a second of said three elements, said driveconnection in eluding said slip clutch, and a shaft driven at a constantspeed from said drum and connected to the third of said elements fordriving the same.

5. In a constant tension web unwinding mechanism, a beam carrying theweb, a drum rotated at a constant speed and over which the web travelsat a constant linear speed, a variable speed transmission comprising afirst shaft, a second shaft, and a speed changing shaft, said firstshaft being driven by said beam, a brake comprising a rotatable drum anda brake shoe frictionally engaging said drum and held stationary, sa idsecond shaft driving said'brake drum, a differential gear train havingthree power transmitting elements, said second shaft drivingone-of'saidelements, a shaft driven at a constant speed from said drumand connected with the second of said elements for driving the same, andmeans for operatively connecting the third of said elements with saidspeed changing shaft.

6. In a constant tension web unwinding mechanism, a beam carrying a web,said web being drawn from the beam at a constant linear speed, avariable speed transmission comprising a first shaft, a second shaft,and a speed changing mechanism, said first shaft being driven by saidbeam, a brake comprising a rotatable drum and a brake shoe frictionallyengaging said drum and held stationary, said second shaft driving saidbrake drum,

and means connected to said speed changing mechanism responsive tochanges in speed of said brake for operating said speed changingmechanism.

7. In a constant tension web unwinding mechanism, a beam carrying a web,a drum rotated at a constant speed and over which the web travels at aconstant linear speed, a variable speed transmission comprising a firstshaft, 8. second shaft, and a speed changing mechanism, said first shaftbeing driven by said beam, a brake, said second shaft driving saidbrake, a differential mechanism having three power transmittingelements, said second shaft driving one of said elements, a shaft drivenat a constant speed from said drum and connected with the second of saidelements for driving the same, and means for connecting the third ofsaid elements with said speed changing mechanism.

8. In an apparatus for maintaining a constant tension on a travelingweb, a rotatable beam carrying a roll of web material which is drawntherefrom at a constant linear speed, a variable speed transmissionhaving an input shaft, an output shaft, and a speed adjusting means,said input shaft being connected to said beam and rotated thereby, abrake comprising a rotatable drum and a brake shoe-frictionally engagingsaid drum and held stationary, said brake being connected to said outputshaft for applying a predetermined drag thereon at a predetermined speedof rotation of said output shaft, said drag tending to decrease thespeed of rotation of said beam as the diameter of said roll decreases,and means connected to said speed adjusting means responsive toconditions affecting the speed of rotation of said input shaft forchanging the speed ratio be- '7 tween said input and output shafts ofsaid variable speed transmission so as to maintain the speed of rotationof said output shaft constant at said predetermined speed.

9. In an unwinding mechanism for web material, an axle, a beam for saidmaterial, said beam being mounted on said axle for rotation therewithand being rotated by unwinding web material therefrom, a rotatablebrake, a complemental brake element for arresting said brake and heldstationary relative thereto, a driving connection between said axle andbrake including a variable speed transmission having input and outputshafts, the input shaft of said transmission being. connected to saidaxle and rotated by unwinding material from said beam, said output shaftbeing connected to said brake, said brake being rotated solely by saidtransmission, and means for automatically maintaining the speed ofrotation of said brake constant, said means adjustingsaid transmission.

10. ,An unwinding mechanism for web material as in claim 9 wherein themeans for automatically maintaining speed of rotation of said brakeconstant comprises a differential gear train having one input thereofconnected to said output shaft, the other input of said differentialgear train being responsive to the linear speed of the unwinding webmaterial, the output of said differential gear train being connected toa fluid motor means, said fiuid motor means adjusting said transmission.

11. An unwinding mechanism for web material as in claim 9 wherein themeans for automatically maintaining speed of rotation of said brakeconstant comprises a pivotally mounted first class lever, one end ofsaid lever contacting the surface of web material, the other end of saidlever being operatively connected to adjust said transmission.

12. ,An unwinding mechanism for web material as in claim 9 wherein themeans for automatically maintaining speed of rotation of said brakeconstant comprises a governor operatively connected to said outputshaft, said governor being responsive to speed variations of said outputshaft and having switch means operatively connected therewith, saidswitch means being responsive to speed variations above and below apreselected value, a source of electric power, a reversible electricmotor, said switch means being in circuit with said motor andcontrolling direction of rotation of said motor in response to speedchanges above and below the preselected value, the output of saidelectric motor adjusting said transmission.

13. An unwinding mechanism for web material as in claim 9 wherein themeans for automatically maintaining speed for rotation of said brakeconstant comprises a fluid motor differential means, one input of saidfluid motor differential means being connected to said output shaft, theother input of said fiuid motor differential means being responsive tothe linear speed of the web material, the output of said fluid motordifferential means adjusting said transmission.

References Cited in the file of this patent UNITED STATES PATENTS2,168,071 Perry Aug. 1, 1939 2,346,903 Caftrey Apr. 18, 1944 2,392,226Butterworth Jan. 1, 1946 2,470,125 Young May 17, 1949 2,582,966 CurtisJan. 22, 1952

